JP3725614B2

JP3725614B2 - Porous plastic filter for fine particle separation

Info

Publication number: JP3725614B2
Application number: JP15632096A
Authority: JP
Inventors: 好美滝口; 洋介江川; ▲隆▼忠西郷; 正雄尾上; 一裕米沢
Original assignee: Nippon Pneumatic Manufacturing Co Ltd; Mitsubishi Plastics Inc
Current assignee: Nippon Pneumatic Manufacturing Co Ltd; Mitsubishi Chemical Corp
Priority date: 1996-05-29
Filing date: 1996-05-29
Publication date: 2005-12-14
Anticipated expiration: 2016-05-29
Also published as: JPH09313834A; TW442319B

Description

【０００１】
【発明の属する技術分野】
本発明は、液体や気体等の流体中に含まれる微粒子を分離濾過するための多孔質プラスチックフィルタであって、ひだ付中空状筒体に構成して濾過面積の増大を図った微粒子分離用多孔質プラスチックフイルタに関する。
【０００２】
【従来の技術】
従来、液体や気体などの流体中に含まれる微粒子を分離ろ過するためのフィルタとしては、粒子状熱可塑性プラスチック材例えば超高分子量ポリエチレンを主成分とする組成物を焼結成形して円筒状多孔質体としたものや、外面に波形ひだを有する長方形状多孔質体としたもの、さらには、合成繊維、ガラス繊維などを密織した布、不織布などの布材を内外で折返して無端状に連続しているひだ付布筒状体としたものなどが提案されている。
【０００３】
【発明が解決しようとする課題】
前者の円筒状多孔質体のものは、その濾過面積は、円筒基体の直径換言すれば長さ一定の場合その半径に依存し、その多孔質体を組込んだ集塵装置の濾過能力は多孔質体の組込み量によって決まることとなり、濾過能力を上げると必然的に大いなる容量の集塵装置が必要となり、結果的に集塵装置が大型化することとなる。
【０００４】
また、後者のひだ付の多孔質体ないしはひだ付の布筒状体のものは、その濾過面積を向上でき、その濾過能力を上げても集塵装置の大型化は避け得るものの、多孔質体のものは中空長方形状となっているので、その形状はある範囲で自由にすることができるが、集塵装置の形状の自由度は少ないものとなる。しかも、布筒状体のものは、布材を折返して無端状となっているので多孔質体のもの以上にその形状は自由にすることができるが、その形状を維持するための補持装置（リティナー）が必要となるものである。
【０００５】
【課題を解決するための手段】
本発明は、このような課題を解決するもので、粉末の熱可塑性プラスチック材を焼結成形して外内に折り箇所を設けたものであって、その折り曲げの数、外寸法、内寸法、肉厚などを任意に選択できると共に垂直あるいは水平に対する自立性を有する多孔質体のひだ付中空状筒体である。すなわち、本発明は、
【０００６】
（１）粉末の熱可塑性プラスチック材を焼結成形した多孔質体からなり、筒体壁の少なくともその一部にひだ部を形成した中空状筒体で構成されていることを特徴とする微粒子分離用多孔質プラスチックフィルタである。
【０００７】
（２）前記中空状筒体の少なくとも一側の表面の水に対する接触角が６０度以上であることを特徴とする。
【０００８】
（３）前記粉末の熱可塑性プラスチック材として、平均粒径が５〜９０μｍのプラスチック材Ａを用いたことを特徴とする。
【０００９】
（４）前記粉末の熱可塑性プラスチック材として、少なくとも、平均粒径が５〜９０μｍのプラスチック材Ａと、平均粒径が９０μｍを超え１，０００μｍ以下のプラスチック材Ｂとを使用してなることを特徴とする。
【００１０】
（５）前記中空状筒体は、少なくとも、平均粒径が小径なプラスチック材Ａを焼結成形してなる小粒子多孔質層と、平均粒径が該プラスチック材Ａより大径なプラスチック材Ｂを焼結成形してなる大粒子多孔質層との複合一体層を具備することを特徴とする。
【００１１】
（６）前記プラスチック材Ａは、平均粒径が１０〜６０μｍの超高分子量ポリエチレンであることを特徴とする。以下、本発明の内容をさらに具体的に説明する。
【００１２】
本発明は、粉末の熱可塑性プラスチック材を焼結成形した多孔質体からなり、筒体壁の少なくともその一部にひだ部を形成した中空状筒体で構成されている。ひだ部は、筒体の外周端に位置する外側屈曲部と、筒体の内周側に位置する内側屈曲部とを交互にあるいは適宜間隔等をおいて設けることにより形成することができる。かかるひだ部を好ましくは全周に又はほぼ半周にわたり形成する。ひだ部を全周に形成したものは分離装置容器内に垂直に配設する場合に好適である。ひだ部をほぼ半周にわたり形成したものは、分離装置容器内に水平に配設する場合に好適である。なぜなら、ひだ部のないほぼ半周を上側には位置させ、ひだ部を下側になるように配置することにより、ひだ部が上側にもある場合に生じる、除去すべき微粒子のひだ部への滞積をなくすることができるからである。
【００１３】
本発明の多孔質プラスチックフィルタは、粉末の熱可塑性プラスチック材、さらにはこれに、これとは平均粒径が相違する粉末の熱可塑性プラスチック材を混合して焼結成形した多孔質体のひだ付中空状筒体で構成される。また、単層構造のもの、あるいはこの層にこれとは平均粒径が相違する粉末の熱可塑性プラスチック材を焼結成形した多孔質層を積層一体化した複層構造のものとすることができる。
【００１４】
本発明に用いる熱可塑性プラスチック材は、超高分子量ポリエチレン、低密度、中密度、高密度ポリエチレン、ポリプロピレンなどのポリオレフィン系樹脂、ポリ塩化ビニル樹脂、ポリサルホン樹脂、ポリエーテルサルホン樹脂、ポリエチレンサルファイド樹脂などであり、さらにこれらにフッ素系樹脂、放射線照射による低密度ポリエチレンを含む架橋ポリオレフィン系樹脂などを混合したものであっても良く、要は焼結成形により多孔質体を得られる粉末の熱可塑性プラスチック材であれば特に限定されるものではないが、これら材料の中でもメルトフローレイト（ＭＦＲ）の小さな材料を使用する方が均一な孔径を有する多孔質体を得る上では好適である。ＭＦＲは、１．０以下が好ましい。
【００１５】
なお、架橋ポリオレフィン系樹脂は、低密度ポリエチレン、中密度ポリエチレン、高密度ポリエチレンなどのポリエチレン、ポリプロピレンなどのポリオレフィン系樹脂に、γ線、χ線などの電離性放射線を吸収線量１０ＫＧｙ以上照射して、架橋度１０％以上としたものである。ここで、電離性放射線を照射することにより、ポリオレフィン系樹脂を高分子化させてメルトフローレイト（ＭＦＲ）の小さな材料とするものであるので、架橋度１０％未満では均一な孔径を有する多孔質体を得る上では好ましくない。
【００１６】
また、本発明の多孔質プラスチックフィルタは、多孔質体が単層構造、あるいは多孔質体を積層一体化した複層構造で構成してあって、前記中空状筒体の少なくとも一側の表面の水に対する接触角が６０度以上であることを特徴としている。すなわち、微粒子を含む液体や気体などの流体が流入する側、あるいは流体が流出する側の表面の水に対する接触角が６０度以上であり、好ましくは９０度以上である。
【００１７】
水に対する接触角が、６０度未満の表面を有するプラスチックフィルタでは、表面の自由エネルギーが大きいため、逆洗を行ってもフィルタ表面に付着した微粒子の払い落しが十分に行われず、目詰まりなどが発生するため、実用上問題がある。
【００１８】
なお、水に対する接触角は、ゴニオメーター式接触角測定器を用いマイクロシリンジでイオン交換水２０μｌを多孔質プラスチックフィルタの表面に滴下し接触角を測定した数値である。
【００１９】
水に対する接触角が６０度以上の表面状態を得る方法としては、多孔質プラスチックフィルタを構成する熱可塑性プラスチック材の種類やその粒子の平均粒径の選定などによって行うことができる。
【００２０】
また、本発明において、好ましくは粉末の熱可塑性プラスチック材は、平均粒径が５〜９０μｍの範囲、さらに好ましくは１０〜６０μｍの範囲のものを使用する。これにより、中空筒状体の表面の水に対する接触角が、６０度以上、好ましくは９０度以上のものを発現させることがよい。
【００２１】
ただし、平均粒径が５〜９０μｍの範囲のものに対して、これより小さな平均粒径の粉末の熱可塑性プラスチック材、あるいはこれより大なる平均粒径の粉末の熱可塑性プラスチック材を所定量添加してあってもよく、要は、その表面の水に対する接触角が、６０度以上、好ましくは９０度以上のものを発現させるものであれば用いることができる。
【００２２】
なお、その添加量は、例えば平均粒径が５μｍ未満だけのもので生ずる成形用金型内への不均一な充填などの現象や、粒径が９０μｍ以上だけのもので生ずる塵芥等の微粒子の不充分な表面捕集能などの現象が生じ得ない範囲であればよい。
【００２３】
多孔質プラスチックフィルタを、多孔質体で単層構造に構成する場合、それを構成する熱可塑性プラスチック材は、その表面の水に対する接触角が６０度以上になるように平均粒径が５〜９０μｍの範囲のものであれば前記した熱可塑性プラスチック材より選択して単独、あるいは混合して使用すれば良い。例えば、平均粒径が５〜９０μｍさらに好ましくは１０〜６０μｍの超高分子量ポリエチレンを単独に使用したものが好適に使用される。
【００２４】
しかし、この他に例えば、これにさらにフッ素系プラスチック材、前記した射線照射による架橋度１０％以上の架橋ポリオレフィン系樹脂、その他から選択された熱可塑性プラスチック材を混合したものや、粒径が５μｍ以上９０μｍ以下の熱可塑性プラスチック材、好ましくは超高分子量ポリエチレンなどに、粒径が９０μｍより大なる熱可塑性プラスチック材、好ましくは超高分子量ポリエチレンなど添加してなるものが使用できる。
【００２５】
なお、フッ素系プラスチック材は、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフルオロアクリルアクリレート、ポリフッ化ビニリデン、ポリフッ化ビニル、ヘキサフルオロプロピレン等、通常知られているものであればよく、特にポリテトラフルオロエチレン、またはポリフルオロアクリルアクリレートが、塵芥等の微粒子に対する非粘着特性を付与するという点からはより好ましい材料である。
【００２６】
このフッ素系プラスチック材の混合割合は、プラスチック材全体に対し、０．１〜５０重量％の範囲であれば良く、好ましくは１〜３０重量％の範囲である。
【００２７】
混合割合が、０．１重量％未満では、その捕集した塵芥等の微粒子の払い落し性能は、多孔質プラスチックフィルタを構成している熱可塑性プラスチック材料自体が有しているものに依存され、所望の払い落し性能は得難く、また、５０重量％を超えると焼結された多孔質プラスチックフィルタの強度低下が著しく、実用上問題を生ずるものである。
【００２８】
さらに、本発明は、前記粉末の熱可塑性プラスチック材として、少なくとも、平均粒径が５〜９０μｍのプラスチック材Ａと、平均粒径が９０μｍを超え１，０００μｍ以下のプラスチック材Ｂとを基材として使用してもよい。両プラスチック材Ａ，Ｂを混合使用する場合、前記した各種熱可塑性プラスチック材が使用できるが、例えば５〜９０μｍの超高分子量ポリエチレンと、粒径が９０μｍを超え１，０００μｍ以下の超高分子量ポリエチレンとを混合したものなどが好適に使用できる。
【００２９】
この超高分子量ポリエチレンの混合割合は、粒径が５〜９０μｍの範囲のものが、全体に対し２０重量％以上でよく、好ましくは４０重量％以上である。
【００３０】
さらに、本発明では、前記中空状筒体は、少なくとも、平均粒径が小径なプラスチック材Ａを焼結成形してなる小粒子多孔質層と、平均粒径が該プラスチック材Ａより大径なプラスチック材Ｂを焼結成形してなる大粒子多孔質層との複合一体層を具備することを特徴とする。すなわち、中空状筒体の除去すべき微粒子を含む液体や気体等の流体が流入する側、あるいは流体が流出する側の一方を粒径が小径な粒子のプラスチック材を焼結成形してなる小粒子多孔質層とし、他方を上記小粒子多孔質層の粒径より大径な粒子のプラスチック材を焼結成形してなる大粒子多孔質層とし、これを複合一体化して少なくとも２層以上で構成するものである。
【００３１】
多孔質プラスチックフィルタが複層構造の場合、小粒子多質層は、塵芥等の微粒子の良好な非粘着性能と表面捕微粒子集性能を発現するものであって、前記単層構造の多孔質プラスチックフィルタの場合で説明したと同様の熱可塑性プラスチック材が適宜使用できる。好ましくは、小粒子多質層は、その表面の水に対する接触角が６０度以上になるように粒径が５μｍ以上９０μｍ以下の範囲のものであれば前記した単層構造の場合と同様の組成のものが好適に使用できる。
【００３２】
また、大粒子多孔質層は、前記の小粒子多孔質層を構成する熱可塑性プラスチック材の平均粒径より大きい平均粒径のプラスック材により構成される。
【００３３】
大粒子多孔質層は、圧力損失が低く高い強度を有し、前記小粒子多孔質層について説明したような超高分子量ポリエチレン、高密度ポリエチレン等のポリエチレンやポリプロピレン等のポリオレフィン系樹脂、ポリ塩化ビニル樹脂、ポリアリレートなどのポリエステル系樹脂、ポリアミド系樹脂、ポリスチレン系樹脂、アクリル系樹脂などが使用できるものであって、平均粒径が９０〜１，０００μｍ、好ましくは１５０〜６００μｍの範囲の焼結により多孔質体を得られる熱可塑性プラスチック材であれば特に限定されるものではなく、例えばぶどう房形状の超高分子量エチレン系ポリオレフィン（超高分子量ポリエチレン等）具体的には、平均粒径が１００〜２００μｍで、且つ嵩密度が０．３５〜０．４５ｇ／cm³のものが機械的強度などの点で好適である。
【００３４】
平均粒径が１，０００μｍを越えるものでは多孔質プラスックフイルタの機械的強度が不十分となりやすい。また平均粒径が９０μｍ未満では多孔質プラスックフイルタを複層にする意味合いが薄弱となる。
【００３５】
小粒子多質層と大粒子多孔質層との厚み構成は、大きな孔径を有する大粒径多孔質層の厚み比率がフイルタ全厚みの３０％以上１００％未満とするのが好ましい。大きな孔径を有する大粒径多孔質層の厚み比率が３０％以下では圧力損失が高くなり、複層構造にする意味合いが薄弱となる。
【００３６】
ここで、流体が流出する側を、平均粒径が小径な粒子の熱可塑性プラスチック材を焼結成形してなる小粒子多質層とし、他方側を、その小粒子多孔質層の粒径より大きい粒径の粒子のプラスック材を焼結成形してなる大粒子多孔質層とした複層の多孔質プラスチックフィルタは、前記した効果に加えて流体内に含有する比較的大なる微粒子を、大粒子多孔質層によっていち早く捕集し、遅れて比較的小なる微粒子を捕集すると共に、所定間隔の逆洗によってその微粒子を分離することによって圧力損失が生じないあるいは低下させることができる。
【００３７】
前記の複層構造の多孔質プラスチックフィルタは、大きな孔径を有する大粒径多孔質層と小さな孔径を有する小粒径多孔質層の複層構造になっていれば、流体の流入側と流出側での層の配置においては特に限定されることなく、流入側に大きな孔径を有する層を配置しても、またその逆であってもフィルタの性能上問題はない。さらには、層の数は限定されず、要求品質に応じ粒径を変化させた層を全体が２層以上になるように設けることができる。
【００３８】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明するが、本発明は以下の実施の形態に限定されるものではない。図１は本発明の実施の形態の一例であるプラスチックフィルタの（ａ）は平面図、（ｂ）は斜視図、図２，図３は他の例のプラスチックフィルタの平面図、図４はプラスチックフィルタの製造方法を説明するための、筒状内型１１と筒状外型１２の断面図、図５はプラスチックフィルタ１により構成されたフィルタユニット２１の（ａ）は平面図、（ｂ）は側面図である。
【００３９】
図１に示すプラスチックフィルタ１は、粉末の熱可塑性プラスチック材を焼結成形した多孔質体からなり、中空状筒体に構成されている。筒体の外周端に位置する外側屈曲部２ａと、筒体の内周側に位置する内側屈曲部２ｂとを交互に設けることにより形成されるひだ部は、筒体の全周にわたって形成されている。各屈曲部２ａ，２ｂはそれぞれ同数８箇所均等な間隔にあり、その横断面形状（平面形状）は星形をなしている。図２に示すプラスチックフィルタ１は外側屈曲部２ａ，内側屈曲部２ｂがそれぞれ同数１２箇所均等な間隔にあり、やはりその横断面形状は星形をなしている。
【００４０】
図３のプラスチックフィルタ１は、筒体の外周端に位置する外側屈曲部２ａと、筒体の内周側に位置する内側屈曲部２ｂとを交互に設けることにより形成されるひだ部を、筒体のほぼ半周にわたって形成した例を示す。筒体壁３のほぼ半周（図左半分）においてはひだ部が形成されておらず、ほぼ円筒形状をなし、筒体壁３の残りの半周（図右半分）は星形をなしている。外側屈曲部２ａが７箇所あるのに対し、内側屈曲部２ｂは６箇所であり外側屈曲部２ａの数より１小さい。なお、上記筒体壁３のほぼ半周は円筒形状をなす曲面の他、複数の平面が連接する多角筒形状となすこともできるが、内周側に向けて凹む屈曲部を設けないようにする。
【００４１】
図示のプラスチックフィルタ１において、筒体壁３の厚み（ｔ），外径（Ｒ１），内径（Ｒ２），ひだの数（ｎ）について、これらの好ましい範囲の一例を示すと、外径（Ｒ１）は２０〜１５０mm，内径（Ｒ２）は｛（２ｔ＋１）ｎ｝×１／２π〜Ｒ１×０．８，厚み（ｔ）は１〜５mm，ひだの数（ｎ）は６個以上のものが好適である。
【００４２】
ここで、外径（Ｒ１）を２０mm未満換言すると内側断面積を５cm²未満にすると、［フィルタの表面積／集塵装置の容積］は、大きくでき好ましいが、実用性特にフィルタとしての濾過面積あるいは払落し面積が小となり過ぎ好ましくない。
【００４３】
本発明のプラスチックフィルタの製造は、プラスチックフィルタを単層構造の多孔質体に構成する場合は、公知の製造方法を適用し得、多孔質プラスチック基材は、所定の粒径の熱可塑性プラスチック材料を、多孔質プラスチックフィルタの断面形状に合わせた形状からなる外型とその内部に挿入する内型とよりなる成形金型を用いる静的成形方法や、ラム押出成形方法、射出成形方法、スクリュウ押出成形方法などの動的成形方法などによって焼結成形して得られる。例えば、図４に示すような断面形状の筒状内型１１と筒状外型１２によって形成される間隙部１３に、粉末のプラスチック材を充填し、これを適宜温度で加熱して焼結後、脱型して得られる。
【００４４】
また、複層構造の多孔質プラスチックフィルタを製造する方法としては、フイルタの形状等により種々の方法が考えられるが、生産効率や各層の厚みの調整が確実にできる次の２つの方法が好ましい。
【００４５】
〔第１方法〕
内型と交換可能な外型により、熱可塑性プラスチック材の粒子を充填できる間隙部を形成し得る成形金型を使用し、
▲１▼ まず、内型の外方に交換可能な外型を配して充填する熱可塑性プラスチック材の粒子の粒径に対応した層厚みを形成できる一次間隙部を形成し、この一次間隙部内に小径の粒子または大径の粒子のプラスチック材を充填した後、これを焼結成形して小粒子多孔質層、または大粒子多孔質層の多孔質プラスチック基材とし、
【００４６】
▲２▼ 次いで、先に使用した外型を取り外して、取り外した外型より内径が大である他の外型に交換・被嵌して一次多孔質プラスチック基材の表層側に二次間隙部を形成し、
【００４７】
▲３▼ さらに続けて、二次間隙部内に前記の小粒子状熱可塑性プラスチック材より大きな粒径の大粒子状熱可塑性プラスチック材、または前記の小粒子状熱可塑性プラスチック材を充填した後、これらを焼結して前記小粒子多孔質層の内表層側に大粒子多孔質層、または大粒子多孔質層の内表層側に小粒子多孔質層を成形する。
【００４８】
▲４▼ これらを冷却後、外型と内型を脱型する。これにより、大粒子多孔質層に、水に対する接触角が６０度以上好ましくは９０度以上の小粒子多孔質層を複合一体化した複層の多孔質プラスチックフィルタを得る。
【００４９】
なお、複層の多孔質プラスチックフィルタの各層は、同種の熱可塑性プラスチック材で構成する方が焼結成型する際に好都合であり、また各層の層間接着力の面からも好ましい。
【００５０】
〔第２方法〕
▲１▼ まず、所定の粒径の粒子の熱可塑性プラスチック材を上記したような適宜手段により一次焼結成形して多孔質プラスチック基材とし、
【００５１】
▲２▼ 次いで、導電性材料によりその多孔質プラスチック基材の多孔質部分の表面に導電性を付与する。なお、導電性の付与は、多孔質プラスチック基材を成形する際に例えばカーボンブラックやカーボンファイバー、金属粉などの導電性材料を基体中に混入させる方法や、成形後の多孔質プラスチック基材の表面に界面活性剤等の液体を塗布する方法などによって行われる。通常、界面活性剤などを塗布する方法が取られるが多孔質プラスチック基材の少なくとも表面に導電性を付与できるものであれば、特に限定されない。
【００５２】
▲３▼ 続いて、多孔質プラスチック基材の表面に、その多孔質プラスチック基材の表面と相溶性を有し、かつその多孔質プラスチック基材を構成する粒子よりも小さい粒径の粒子のプラスチック材を噴出させる静電気的に塗着する塗装方法によって、小粒子のプラスチック材を被着・積層し、
【００５３】
▲４▼ さらに続けて、この多孔質プラスチック基材を、所定温度に設定した加熱炉などで二次焼結する。これにより、大粒子多孔質層に、水に対する接触角が６０度以上好ましくは９０度以上の小粒子多孔質層を複合一体化した複層の多孔質プラスチックフィルタを得ることができる。
【００５４】
これらに使用する成形金型は、多孔質プラスチックフィルタの断面形状に合わせた前記した静的成形方法における外型と内型とよりなる成形金型、動的成形方法における押出用口金や射出用成形金型などである。
【００５５】
上記のようにして得られる多孔質プラスチックフィルタは、通常、複数本を組合せて図５に示すようなフィルタユニット２１とし、これを所定の形状の分離装置用容器内に垂直または水平に懸架等の手段により取り付けて分離装置として使用する。
【００５６】
図５に示すフィルタユニット２１は、多孔質プラスチックフィルタ１を略板状の支持体２２に取付けたものであって、プラスチックフィルタ１の一方の端部を孔の開いた支持体２２に嵌着等の手段により固定し、他方の端部の開口部を蓋体２３で閉塞したものである。
【００５７】
この支持体２２および蓋体５は、金属や各種の合成樹脂例えば硬質のポリオレフィン樹脂、ポリ塩化ビニル等の熱可塑性樹脂や反応型の熱硬化性樹脂などが使用されるが、反応型の液状ポリウレタン樹脂が成形加工性や寸法安定性から好ましい。
【００５８】
そして、このフィルタユニットに導電性を付与する必要がある場合には、多孔質プラスチックフィルタを焼結成形する際に超高分子量ポリエチレンに１〜１０％程度のカーボンブラックを添加するとともに支持体および蓋体にも同様にカーボンブラックを添加した導電性材料を使用する。
【００５９】
なお、反応型の液状ポリウレタン樹脂を使用する場合主剤のポリオールおよび硬化剤に平均糸長０．１〜１．０mmの炭素繊維を３〜１０重量％添加したものが、残留歪みが小さく高い寸法精度と帯電防止性能を兼ね備えたものとなり、好適である。
【００６０】
なお、ひだ部を中空状筒体のほぼ半周にわたり形成したフィルタで構成したフィルタユニットは、主として所定の形状の分離装置用容器内に、その半周を円筒形とした側（ひだ部を形成しない側）を上面側（除去すべき微粒子が落下して来る側）にして水平方向に配置して取り付けて分離装置すると、落下して来る除去すべき微粒子がプラスチックフィルタのひだ部分に滞積しなくて好ましい。しかし、このフィルタユニットを、星形ひだ付中空状筒体と同様に垂直方向に懸架して取り付けて分離装置としてもよい。
【００６１】
【実施例】
以下、本発明の実施例を説明するが、本発明は以下の実施例によりその範囲が限定されるものではない。多孔質プラスチックフィルタを以下に記載の内容にて製造し、フィルタとしての性能評価を下記の方法により評価した。その結果を各表に示す。
【００６２】
「粒子脱落の有無」……逆洗による払い落しの際に、フィルタ粒子の脱落がなく良好なもの（○）、逆洗による払い落しの際に、フィルタ粒子の脱落が一部認められるもの（△）、逆洗による払い落しの際に、フィルタ粒子の脱落があるものを（×）とした。ただし、ここでフィルタ粒子とは、フィルタ面に設けた非粘着特性を有する粒子あるいはフィルタを構成しているプラスチックを指す。
【００６３】
「粉体払い落し性」……逆洗によるフィルタ表面に付着した微粒子の払い落しが極めて良好なもの（◎）、逆洗によるフィルタ表面に付着した微粒子の払い落しが良好なもの（○）、逆洗によるフィルタ表面に付着した微粒子の払い落しが一部悪いもの（△）、逆洗によるフィルタ表面に付着した微粒子の払い落しが悪いものを（×）とした。
【００６４】
「微粒子捕集性能」……払い落された微粒子の流体流出側への混入が認められないもの（○）、払い落された微粒子の流体流出側への混入が一部認められるもの（△）、払い落された微粒子の流体流出側への混入が認められるもの（×）とした。
【００６５】
「対水接触角／度」……ゴニオメーター式接触角測定器（エルマ社製Ｇ−１型）により測定した数値である。
【００６６】
「圧力損失／mmＡｑ」…微粒子を含まない空気を１ｍ／ｍｉｎで吸引した時の値である。
【００６７】
〔実施例１〕
平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、断面形状が図５に示す筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み３mmを得るに必要な幅の間隙部に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、図１に示す肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００６８】
〔比較例１〕
平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、円筒状内型と円筒状外型から形成される最終の多孔質プラスチックフィルタ厚み３mmを得るに必要な幅の間隙部に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、肉厚３mmの断面形状が円筒形の多孔質プラスチックフィルタを得た（外径は実施例１と同一）。
【００６９】
【表１】

【００７０】
表１に示したように、各例においては、粒子の脱落や流体流出側への微粒子の混入、さらには粉体の払い落し性能についても問題なく良好であるが、実施例１の星形形状のフィルタは、円形形状のフィルタに比較して圧力損失が低く、しかも単位容積当たりのろ過面積が多くなるので、分離装置のろ過容量、装置容量、設置面積などの選択が容易にでき、設計施工上も優れるものである。
【００７１】
〔実施例２〕
平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、実施例１と同様の断面形状の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み２mmを得るに必要な幅の間隙部に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、肉厚２mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００７２】
〔実施例３〕
平均粒径が１１０μｍでメルトフローレイトが０．０１以下の分子量４００万の超高分子量ポリエチレンを、実施例１と同様の断面形状が星形の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み３mmを得るに必要な幅の間隙部に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００７３】
〔実施例４〕
平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、実施例１と同様の断面形状が星形の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み２mmを得るに必要な幅の間隙部に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、次いで、その表面に界面活性剤を塗布して肉厚２mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００７４】
【表２】

【００７５】
表２に示したように、実施例２においては、粒子の脱落や流体流出側への微粒子の混入もなく、また粉体の払い落し性能についても問題なかったが、実施例３においては、孔径が大きいため、流体流出側への微粒子の混入が一部認められた。実施例４においては、粉体の払い落し性に間題があった。また、圧力損失は、いずれも実用上は問題ないが、特に実施例３が良好である。
【００７６】
〔実施例５〜９〕
平均粒径が４０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンと、平均粒径が１５０μｍでメルトフローレイトが０．０１以下の分子量４００万の塊状の超高分子量ポリエチレンとを、それぞれ表３に記載の割合（重量％）で混合した組成物を、実施例１と同様の断面形状の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み２mmを得るに必要な幅の間隙部に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、肉厚２mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００７７】
【表３】

【００７８】
表３に示したように、実施例５〜９のいずれも粒子の脱落および粉体払い落し性能について問題なく、また、圧力損失については実施例５が若干高いが実用上問題はない。小粒径材料の割合が低い実施例９では、流体流出側への微粒子の混入が一部認められた。
【００７９】
〔実施例１０〕
平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンと平均粒径が０．２μｍのＰＴＦＥ粉体を、その混合割合が全体に対し超高分子量ポリエチレンが９５重量％、およびΡＴＦＥ粉体が５重量％になるようにブレンダーにて機械的に混合し焼結用材料とした。この材料を、実施例１と同様の断面形状の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み２mmを得るに必要な幅の間隙部に充填し、１６０〜２２０℃の温度で３０〜９０分加熱し、肉厚２mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００８０】
〔実施例１１〕
平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２０万の超高分子量ポリエチレンと溶媒に溶したポリフルオロアルキルアクリレートを、その混合割合が全体に対し超高分子量ポリエチレンが９９重量％、およびポリフルオロアルキルアクリレート成分が１重量％になるようにブレンダーにて機械的に混合し焼結用材料とした。この材料を、実施例１と同様の断面形状の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み２mmを得るに必要な幅の間隙部に充填し、１６０〜２２０℃の温度で３０〜９０分加熱し、肉厚２mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００８１】
【表４】

【００８２】
表４に示したように、実施例１０，１１においては、粒子の脱落や粉体の払い落し性能に問題はなく、また、払い落し性能を評価する上で１つの目安となる対水接触角も大きな値となった。実施例１０において、ＰＴＦＥ粒子が脱落しない理由については現在のところ定かでないが、金型内で超高分子量ポリエチレンが溶融膨脹する際に、ＰＴＦＥ粒子がある程度超高分子量ポリエチレンの粒子内部に埋封されるためと考えられる。一方、実施例１１において、ポリフルオロアルキルアクリレートが脱落しない理由は、過熱により超高分子量ポリエチレンの粒子側に親油基が、表面側にパーフルオロアルキル基が高密度に配向されているためと考えられる。また、圧力損失は、いずれも実用上は問題ない。
【００８３】
〔実施例１２〕
断面形状が実施例１と同様の断面形状の筒状内型１個と、筒状内型よりも大径であってかつ交換可能な筒状外型を２個計３個を準備し、まず、平均粒径が１６０μｍでメルトフローレイトが０．０１以下の分子量４００万の超高分子量ポリエチレンを、層の厚み比率が最終の多孔質プラスチックフィルタ厚み３mmの７０％を得るに必要な幅の一次間隙部を有する筒状内型と筒状外型からなる成形金型の一次間隙部内に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、孔径の大きな大粒径多孔質層を得た後、続いて、この筒状外型をその筒状外型より内径が大なる筒状外型に交換して前記の大粒径多孔質層の外側に、平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、層の厚み比率が最終の多孔質プラスチックフィルタ厚み３mmの３０％になり得るに必要な幅の二次間隙部を形成して大なる筒状外型を配置し、この二次間隙部内に、前記の平均粒径が３０μｍの超高分子量ポリエチレンを充填し、これを再度１６０〜２２０℃の温度で３０分加熱し、円筒の外層側即ち、流体の流入側に孔径の小さな小粒径多孔質層が、円筒の内層側即ち、流体の流出側に孔径の大きな大粒径多孔質層が形成された２層の全肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００８４】
〔実施例１３〕
実施例１２と同一の筒状内型および筒状外型を使用し、まず、平均粒径が３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを層の厚み比率が最終の多孔質プラスチックフィルタ厚み３mmの３０％を得るに必要な幅の一次間隙部を有する筒状内型と筒状外型からなる成形金型の一次間隙部内に充填し、これを１６０〜２２０℃の温度で３０分加熱し、孔径の小さな小粒径多孔質層を得た後、実施例１３と同様にして筒状外型を取替え、平均粒径が１６０μｍでメルトフローレイトが０．０１以下の分子量４００万の超高分子量ポリエチレンを層の厚み比率がフイルタの全厚みの７０％になるように、上記小粒径多孔質層の外側と取替えた筒状外型を配して設けた二次間隙部内に充填し、これを再度１６０〜２２０℃の温度で３０分加熱し、円筒の外層側即ち、流体の流入側に孔径の大きな大粒径多孔質層が、円筒の内層側即ち、流体の流出側に孔径の小さな小粒径多孔質層が形成された２層の全肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００８５】
〔実施例１４〕
平均粒径が１６０μｍでメルトフローレイトが０．０１以下の分子量４００万の超高分子量ポリエチレンを、実施例１と同様の断面形状の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み３mmを得るに必要な幅の間隙部に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、超高分子量ポリエチレン単独の断面形状が星形の多孔質プラスチックフィルタを得た。
【００８６】
【表５】

【００８７】
表５に示したように、実施例１２，１３においては、粒子の脱落や流体流出側への微粒子の混入もなく、また圧力損失も小さく問題ないが、実施例１４においては、孔径が大きすぎるため、流体流出側への微粒子の混入が認められた。なお、圧力損失は、いずれも実用上は問題ないが、特に実施例１４が良好である。
【００８８】
〔実施例１５〕
平均粒径が１７０μｍでメルトフローレイトが０．０１以下の分子量４００万の超高分子量ポリエチレンを、実施例１と同様の断面形状の筒状内型と筒状外型から形成される最終の多孔質プラスチックフィルタ厚み３mmを得るに必要な幅の間隙部に充填し、これを１５０〜２００℃の温度で６０分加熱し、肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。この多孔質プラスチック基材の表面に界面活性剤を塗布してその基材の表面に導電性を付与した後、平均粒径３０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、自動静電塗装機を用いて、使用電圧６０ΚＶ、霧化空気圧１．５Ｋｇ／cm²にて静電塗装して、その基材の表面に平均粒径３０μｍの分子量２００万の超高分子量ポリエチレンで厚さ２００μｍの多孔質層を被着積層した。これをさらに１５０〜２００℃の温度の加熱炉内で３０分加熱して焼結成形して、その基材の表面に基材の孔径より小径の多孔質層を被着溶着した２層の肉厚ほぼ３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００８９】
〔実施例１６〕
平均粒径が３４０μｍでメルトフローレイトが０．０１以下の分子量３３０万の超高分子量ポリエチレンを、先端部に最終の多孔質プラスチックフィルタ厚み３mmを得るに必要な幅の円筒状開口を有する口金を設けたラム式押出機で焼結成形して、肉厚３mmの円筒形状の多孔質プラスチック基材を得た。この多孔質プラスチック基材を、実施例１５と同じ静電塗装条件で静電塗装して、その基材の表面に平均粒径３０μｍの分子量２００万の超高分子量ポリエチレンで厚さ２００μｍの多孔質層を被着積層し、これをさらに実施例１５と同様の加熱条件で焼結成形して、その基材の表面に基材の孔径より小径の多孔質層を被着積層した２層の肉厚ほぼ３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００９０】
【表６】

【００９１】
表６に示したように、小粒径のプラスチック材を静電塗装してなる実施例１５，１６においては、粒子の脱落や流体流出側ヘの微粒子の混入もなく、フィルタとしての性能に優れている。また、圧力損失は、いずれも良好である。
【００９２】
〔実施例１７〕
実施例１２と同一の筒状内型および筒状外型を使用し、先ず、平均粒径が１６０μｍでメルトフローレイトが０．０１以下の分子量４００万の超高分子量ポリエチレンを、層の厚み比率が最終の多孔質プラスチックフィルタ厚み３mmの７０％を得るに必要な幅の一次間隙部を有する筒状内型と筒状外型からなる成形金型の一次間隙部内に充填し、これを１６０〜２２０℃の温度で３０分加熱し、孔径の大きな大粒径多孔質層を得た後、実施例１２と同様にして筒状外型を取替え、平均粒径が２６μｍの低密度ポリエチレンに２００ＫＧｙのγ線を照射して得た架橋度７７％（メルトフローレイト０．０１以下）の小粒径のプラスチック材を、層の厚み比率がフイルタの全厚みの３０％になるように、上記大粒径多孔質層の外側と取替えた筒状外型を配して設けた二次間隙部内に充填し、これを再度１６０〜２２０℃の温度で３０分加熱し、円筒の外層側即ち、流体の流入側に孔径の小きな小粒径多孔質層が、円筒の内層側即ち、流体の流出側に孔径の大さな大粒径多孔質層が形成された２層の全肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００９３】
〔実施例１８〕
実施例１５と同様の方法で平均粒径が１７０μｍの分子量４００万の超高分子量ポリエチレンで、肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。この多孔質プラスチック基材の表面に界面活性剤を塗布してその基材の表面に導電性を付与した後、実施例１７で使用したと同様の架橋度７７％の小粒径のプラスチック材を、実施例１５と同じ静電塗装方法で静電塗装して、その基材の表面に平均粒径２６μｍの超高分子量ポリエチレンで厚さ１７０μｍの多孔質層を被着積層し、これをさらに実施例１５と同様の加熱条件で焼結成形して、その基材の表面に基材の孔径よりり小径の多孔質層を被着積層した２層の肉厚ほぼ３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００９４】
【表７】

【００９５】
表７に示したように、低密度ポリエチレンに２００ＫＧｙのγ線を照射して得た架橋度７７％の小粒径のプラスチック材料を、筒状等の形状からなる外型とその内部に挿入する内型とよりなる成形金型を用いる静的成形方法や、静電塗装方法の実施例１７，１８においては、粒子の脱落や流体流出側ヘの微粒子の混入もなく、フィルタとしての性能を充分に備えている。また、圧力損失は、いずれも良好である。
【００９６】
〔実施例１９〕
実施例１２と同一の筒状内型および筒状外型を使用し、まず、平均粒径が１５０μｍで嵩密度が０．４２ｇ／cm³の樹脂粒子がぶどう房形状の分子量４００万の超高分子量ポリエチレンを、層の厚み比率が最終の多孔質プラスチックフィルタ厚み３mmの７０％を得るに必要な幅の一次間隙部を有する筒状内型と筒状外型からなる成形金型の一次間隙部内に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、孔径の大きな大粒径多孔質層を得た後、実施例１２と同様にして筒状外型を取替え、平均粒径が４０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、層の厚み比率がフィルタの全厚みの３０％になるように、上記大粒径多孔質層の外側の筒状外型と取替えた筒状外型を配して設けた間隙部に充填し、これを再度１６０〜２２０℃の温度で２０〜３０分加熱し、円筒の外層側即ち、流体の流入側に孔径の小さな小粒径多孔質層を有し、円筒の内層側即ち、流体の流出側に孔径の大きな大粒径多孔質層を有する２層の全肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００９７】
〔実施例２０〕
実施例１２と同一の筒状内型および筒状外型を使用し、まず、平均粒径が１２０μｍで嵩密度が０．４６ｇ／cm³の樹脂粒子が塊状の分子量４００万の超高分子量ポリエチレンを、層の厚み比率が最終の多孔質プラスチックフィルタ厚み３mmの７０％を得るに必要な幅の一次間隙部を有する筒状内型と筒状外型からなる成形金型の一次間隙部内に充填し、これを１６０〜２２０℃の温度で３０〜９０分加熱し、孔径の大きな大粒径多孔質層を得た後、実施例１２と同様にして筒状外型を取替え、平均粒径が４０μｍでメルトフローレイトが０．０１以下の分子量２００万の超高分子量ポリエチレンを、層の厚み比率がフイルタの全厚みの３０％になるように、上記大粒径多孔質層の外側の筒状外型と取替えた筒状外型を配して設けた二次間隙部内に充填し、これを再度１６０〜２２０℃の温度で２０〜３０分加熱し、円筒の外層側即ち、流体の流入側に孔径の小きな小粒径多孔質層が、円筒の内層側即ち、流体の流出側に孔径の大さな大粒径多孔質層が形成された２層の全肉厚３mmの断面形状が星形の多孔質プラスチックフィルタを得た。
【００９８】
【表８】

【００９９】
表８に示したように、樹脂粒子がぶどう房形状の超高分子量ポリエチレンを使用した実施例１９においては、圧力損失の低下を招くことなく高い引張強度、伸びを示している。実施例２０においては、圧力損失の低下は招くことはないが引張強度、伸びが低下していることを示している。
【０１００】
【発明の効果】
本発明に係る全周に又はほぼ半周にわたりひだ部を形成した中空状筒体で構成された微粒子分離用多孔質プラスチックフィルタは、単体のフィルタエレメントとして使用した場合は無論のことこれを集合させたフィルタユニットとして利用した場合、単なる円筒状のものに比較し１本当たり１．５倍〜数倍の濾過面積を持たせることが可能となり、これを集塵装置に組み込んだ場合、集塵装置の大きさを１／２〜１／３以下に小型化することができ、産業上大きな効果を奏する。
【０１０１】
しかも、本発明の多孔質プラスチックフィルタは、粉末の熱可塑性プラスチック材を焼結成形してあるので、フィルタとしての各種の優れた特性を有する多孔質体であると共に、剛直性を有することより、フィルタエレメントあるいはフィルタユニットの形状を維持するための補持装置（リティナー）などを必要とすることのない自己直立性あるいは形態保持性のあるフィルタである。
【０１０２】
また、本発明の多孔質プラスチックフィルタは、中空状筒体の少なくとも一側の表面の水に対する接触角が、６０度以上、好ましくは９０度以上であるため、良好な払い落し性能を有する。
【０１０３】
また、粉末の熱可塑性プラスチック材として、平均粒径が５〜９０μｍの熱可塑性プラスチック材Ａを用いる構成、また、平均粒径が５〜９０μｍのプラスチック材Ａと、平均粒径が９０μｍを超え１，０００μｍ以下のプラスチック材Ｂとを使用してなる構成、平均粒径が小径なプラスチック材Ａを焼結成形してなる小粒子多孔質層と、平均粒径が該プラスチック材Ａより大径なプラスチック材Ｂを焼結成形してなる大粒子多孔質層との複合一体層を具備する構成により、良好な払い落し性能と、表面捕集性能を兼備しながらも、従来のようにＰＴＦＥ粒子等が脱落し、捕集された微粒子中に混入するなどの問題のない微粒子分離用多孔質プラスチックフィルタを提供することができる等の効果を奏する。
【図面の簡単な説明】
【図１】本発明の実施の形態の一例であるプラスチックフィルタ１の（ａ）は平面図、（ｂ）は斜視図である。
【図２】他の例のプラスチックフィルタ１の平面図である。
【図３】他の例のプラスチックフィルタ１の平面図である。
【図４】プラスチックフィルタの製造方法を説明するための、筒状内型１１と筒状外型１２の断面図である。
【図５】プラスチックフィルタ１により構成されたフィルタユニット２１の（ａ）は平面図、（ｂ）は側面図である。
【符号の説明】
１プラスチックフィルタ
２ａ外側屈曲部
２ｂ内側屈曲部
３筒体壁
１１筒状内型
１２筒状外型
２１フィルタユニット
２２支持体
２３蓋体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a porous plastic filter for separating and filtering fine particles contained in a fluid such as a liquid or gas, and is a porous plastic filter for separating fine particles which is configured as a pleated hollow cylindrical body to increase the filtration area. Quality plastic filter.
[0002]
[Prior art]
Conventionally, as a filter for separating and filtering fine particles contained in a fluid such as liquid or gas, a cylindrical porous material is formed by sintering a composition composed mainly of a particulate thermoplastic material such as ultrahigh molecular weight polyethylene. Fabricated material, rectangular porous material with corrugated pleats on the outer surface, and cloth materials such as densely woven synthetic fibers and glass fibers, and non-woven fabrics are folded back and forth to make them endless. A continuous pleated cloth cylindrical body has been proposed.
[0003]
[Problems to be solved by the invention]
In the former cylindrical porous body, the filtration area depends on the diameter of the cylindrical substrate, in other words, when the length is constant, and the filtration capacity of the dust collector incorporating the porous body is porous. It depends on the amount of the material incorporated, and increasing the filtration capacity inevitably requires a large capacity dust collector, resulting in an increase in the size of the dust collector.
[0004]
In addition, the latter pleated porous body or pleated cloth cylindrical body can improve its filtration area, and even if its filtration capacity is increased, the size of the dust collector can be avoided, but the porous body Since the object has a hollow rectangular shape, its shape can be freely set within a certain range, but the degree of freedom of the shape of the dust collector is small. Moreover, the cloth cylindrical body is endless by folding the cloth material, so that the shape can be made more freely than that of the porous body, but a supporting device for maintaining the shape (Retainer) is required.
[0005]
[Means for Solving the Problems]
The present invention solves such a problem, and is formed by sintering a powdered thermoplastic material to provide a fold portion inside and outside, the number of the folds, the outside dimensions, the inside dimensions, It is a hollow pleated hollow cylindrical body that can be arbitrarily selected in thickness and has self-supporting property in the vertical or horizontal direction. That is, the present invention
[0006]
(1) Fine particle separation, characterized by comprising a hollow cylindrical body made of a porous body obtained by sintering powdered thermoplastic material and having a pleated portion formed on at least a part of the cylindrical wall. Porous plastic filter.
[0007]
(2) The contact angle with respect to water of the surface of at least one side of the hollow cylindrical body is 60 degrees or more.
[0008]
(3) A plastic material A having an average particle diameter of 5 to 90 μm is used as the powdered thermoplastic material.
[0009]
(4) As the powdered thermoplastic material, at least a plastic material A having an average particle diameter of 5 to 90 μm and a plastic material B having an average particle diameter of more than 90 μm and 1,000 μm or less are used. Features.
[0010]
(5) The hollow cylindrical body includes at least a small particle porous layer formed by sintering a plastic material A having a small average particle diameter, and a plastic material B having an average particle diameter larger than that of the plastic material A. It is characterized by comprising a composite integral layer with a large particle porous layer formed by sintering.
[0011]
(6) The plastic material A is an ultra high molecular weight polyethylene having an average particle size of 10 to 60 μm. Hereinafter, the content of the present invention will be described more specifically.
[0012]
The present invention comprises a hollow cylindrical body made of a porous body obtained by sintering and molding a powdered thermoplastic material and having a pleated portion formed on at least a part of the cylindrical wall. The pleat portion can be formed by providing an outer bent portion located at the outer peripheral end of the cylindrical body and an inner bent portion positioned on the inner peripheral side of the cylindrical body alternately or at an appropriate interval. Such pleats are preferably formed over the entire circumference or substantially half a circumference. What formed the pleat part in the perimeter is suitable when arrange | positioning vertically in a separator container. What formed the pleat part over the substantially half circumference is suitable when arrange | positioning horizontally in a separator container. This is because by placing the almost half circumference without pleats on the upper side and placing the pleats on the lower side, the stagnation of fine particles to be removed that occur when the pleats are also on the upper side. This is because the product can be eliminated.
[0013]
The porous plastic filter of the present invention has a pleated structure of a porous body obtained by sintering and molding a powdered thermoplastic material, and further mixing a powdered thermoplastic material having an average particle size different from that of the powdered thermoplastic material. It is composed of a hollow cylinder. Further, it can be of a single layer structure or a multilayer structure in which a porous layer obtained by sintering and molding a powdered thermoplastic material having an average particle size different from that of this layer is laminated and integrated. .
[0014]
The thermoplastic material used in the present invention includes ultrahigh molecular weight polyethylene, low density, medium density, high density polyethylene, polyolefin resins such as polypropylene, polyvinyl chloride resin, polysulfone resin, polyethersulfone resin, polyethylene sulfide resin, etc. Further, it may be a mixture of a fluorine-based resin, a crosslinked polyolefin-based resin containing low-density polyethylene by radiation irradiation, or the like. In short, a powdered thermoplastic that can obtain a porous body by sintering molding The material is not particularly limited, but among these materials, it is preferable to use a material having a small melt flow rate (MFR) in order to obtain a porous body having a uniform pore diameter. MFR is preferably 1.0 or less.
[0015]
In addition, the crosslinked polyolefin resin is irradiated with ionizing radiation such as γ rays and χ rays to a polyolefin resin such as low density polyethylene, medium density polyethylene, high density polyethylene, and polypropylene, and an absorbed dose of 10 KGy or more. The degree of crosslinking is 10% or more. Here, by irradiating with ionizing radiation, the polyolefin resin is polymerized into a material having a low melt flow rate (MFR). Therefore, a porous material having a uniform pore size when the degree of crosslinking is less than 10%. It is not preferable for obtaining a body.
[0016]
In the porous plastic filter of the present invention, the porous body has a single-layer structure or a multilayer structure in which porous bodies are laminated and integrated, and the porous plastic filter has at least one surface of the hollow cylindrical body. The contact angle with water is 60 degrees or more. That is, the contact angle with respect to water on the surface into which a fluid such as liquid or gas containing fine particles flows or the surface from which the fluid flows out is 60 degrees or more, and preferably 90 degrees or more.
[0017]
A plastic filter having a surface with a water contact angle of less than 60 degrees has a large free energy on the surface. Therefore, even if backwashing is performed, fine particles adhering to the filter surface are not sufficiently removed, and clogging may occur. This is a practical problem.
[0018]
The contact angle with water is a numerical value obtained by dropping 20 μl of ion-exchanged water onto the surface of the porous plastic filter with a microsyringe using a goniometer-type contact angle measuring device and measuring the contact angle.
[0019]
As a method for obtaining a surface state having a contact angle with water of 60 degrees or more, it can be performed by selecting the kind of thermoplastic material constituting the porous plastic filter, the average particle diameter of the particles, or the like.
[0020]
In the present invention, the powdery thermoplastic material preferably has a mean particle size in the range of 5 to 90 μm, more preferably in the range of 10 to 60 μm. Thereby, the contact angle with respect to water of the surface of the hollow cylindrical body is preferably 60 degrees or more, preferably 90 degrees or more.
[0021]
However, for those having an average particle size in the range of 5 to 90 μm, a predetermined amount of powdered thermoplastic material having an average particle size smaller than this, or a thermoplastic material having an average particle size larger than this is added. In short, it can be used as long as the surface has a contact angle with water of 60 degrees or more, preferably 90 degrees or more.
[0022]
Note that the amount added is, for example, a phenomenon such as non-uniform filling into a molding die that occurs when the average particle size is less than 5 μm, or fine particles such as dust that occurs when the particle size is only 90 μm or more. It may be in a range in which a phenomenon such as insufficient surface collection ability cannot occur.
[0023]
When the porous plastic filter is constructed in a single layer structure with a porous body, the thermoplastic material constituting the porous filter has an average particle diameter of 5 to 90 μm so that the contact angle with water on the surface is 60 degrees or more. If it is the thing of the range, it is sufficient to select from the thermoplastic material mentioned above, and to use alone or in mixture. For example, an ultra-high molecular weight polyethylene having an average particle size of 5 to 90 μm, more preferably 10 to 60 μm, is preferably used.
[0024]
However, in addition to this, for example, a fluorine plastic material, a cross-linked polyolefin resin having a degree of cross-linking of 10% or more by irradiation with radiation, and a thermoplastic plastic material selected from others, or a particle size of 5 μm A material obtained by adding a thermoplastic material having a particle size larger than 90 μm, preferably an ultra high molecular weight polyethylene, to a thermoplastic material having a particle size of 90 μm or less, preferably ultra high molecular weight polyethylene can be used.
[0025]
The fluorine-based plastic material may be any conventionally known material such as polytetrafluoroethylene (PTFE), polyfluoroacryl acrylate, polyvinylidene fluoride, polyvinyl fluoride, hexafluoropropylene, and particularly polytetrafluoroethylene. Alternatively, polyfluoroacrylacrylate is a more preferable material from the viewpoint of imparting non-adhesive properties to fine particles such as dust.
[0026]
The mixing ratio of the fluorine-based plastic material may be in the range of 0.1 to 50% by weight, preferably in the range of 1 to 30% by weight, with respect to the entire plastic material.
[0027]
When the mixing ratio is less than 0.1% by weight, the removal performance of the collected fine particles such as dust is dependent on what the thermoplastic material itself constituting the porous plastic filter has, Desirable removal performance is difficult to obtain, and if it exceeds 50% by weight, the strength of the sintered porous plastic filter is remarkably lowered, which causes a practical problem.
[0028]
Furthermore, the present invention uses, as a base material, at least a plastic material A having an average particle diameter of 5 to 90 μm and a plastic material B having an average particle diameter of more than 90 μm and not more than 1,000 μm as the powdered thermoplastic material. May be used. When both plastic materials A and B are used in combination, the above-mentioned various thermoplastic materials can be used. For example, ultra high molecular weight polyethylene having a particle size of more than 90 μm and not more than 1,000 μm, for example, ultra high molecular weight polyethylene having 5 to 90 μm. And the like can be suitably used.
[0029]
The mixing ratio of the ultra-high molecular weight polyethylene may be 20% by weight or more, preferably 40% by weight or more, based on the total particle diameter of 5 to 90 μm.
[0030]
Furthermore, in the present invention, the hollow cylindrical body includes at least a small particle porous layer formed by sintering a plastic material A having a small average particle diameter, and an average particle diameter larger than that of the plastic material A. It comprises a composite integral layer with a large particle porous layer formed by sintering plastic material B. That is, a small plastic particle having a small particle diameter is sintered on one side of the hollow cylindrical body into which a fluid such as liquid or gas containing fine particles to be removed flows or the fluid flows out. A particle porous layer is formed, and the other is formed into a large particle porous layer formed by sintering and molding a plastic material having a particle size larger than the particle size of the small particle porous layer. It constitutes.
[0031]
When the porous plastic filter has a multi-layer structure, the small particle multi-layer expresses good non-adhesive performance of fine particles such as dust and surface trapping particle collecting performance, and the porous plastic of the single-layer structure The same thermoplastic material as described in the case of the filter can be used as appropriate. Preferably, the small particle multi-layer has the same composition as that of the single-layer structure described above as long as the particle diameter is in the range of 5 μm or more and 90 μm or less so that the contact angle with water on the surface is 60 degrees or more. Can be preferably used.
[0032]
The large particle porous layer is composed of a plastic material having an average particle diameter larger than the average particle diameter of the thermoplastic material constituting the small particle porous layer.
[0033]
The large particle porous layer has high strength with low pressure loss, such as the ultra-high molecular weight polyethylene, the high density polyethylene such as polyethylene described in the small particle porous layer, and the polyolefin resin such as polypropylene, polyvinyl chloride. Resins, polyester resins such as polyarylate, polyamide resins, polystyrene resins, acrylic resins and the like can be used, and the average particle size is 90 to 1,000 μm, preferably 150 to 600 μm. The material is not particularly limited as long as it is a thermoplastic material that can obtain a porous body by, for example, a vine-shaped ultrahigh molecular weight ethylene polyolefin (ultra high molecular weight polyethylene, etc.). -200 [mu] m and bulk density of 0.35-0.45 g / cm ^Three Are preferable in terms of mechanical strength and the like.
[0034]
When the average particle size exceeds 1,000 μm, the mechanical strength of the porous plastic filter tends to be insufficient. On the other hand, when the average particle size is less than 90 μm, the meaning of making the porous plastic filter as a multilayer is weak.
[0035]
The thickness constitution of the small particle porous layer and the large particle porous layer is preferably such that the thickness ratio of the large particle size porous layer having a large pore size is 30% or more and less than 100% of the total thickness of the filter. When the thickness ratio of the large-diameter porous layer having a large pore diameter is 30% or less, the pressure loss becomes high, and the meaning of making a multilayer structure becomes weak.
[0036]
Here, the side from which the fluid flows is a small particle multi-layer formed by sintering a thermoplastic material having a small average particle diameter, and the other side is smaller than the particle diameter of the small particle porous layer. In addition to the above-described effects, the multilayer porous plastic filter having a large particle porous layer formed by sintering and molding a plastic material having a large particle size has a large amount of relatively large particles contained in the fluid. By collecting the fine particles early by the porous particle layer and collecting relatively small particles with a delay, the fine particles are separated by backwashing at a predetermined interval so that pressure loss does not occur or can be reduced.
[0037]
The porous plastic filter having the multi-layer structure has a multi-layer structure of a large particle size porous layer having a large pore size and a small particle size porous layer having a small pore size. There is no particular limitation on the arrangement of the layers, and there is no problem in the performance of the filter even if a layer having a large pore diameter is arranged on the inflow side and vice versa. Furthermore, the number of layers is not limited, and the number of layers with the particle size changed according to the required quality can be provided so that the whole is two or more layers.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. 1A is a plan view of a plastic filter as an example of an embodiment of the present invention, FIG. 1B is a perspective view, FIG. 2 and FIG. 3 are plan views of another example of a plastic filter, and FIG. FIG. 5 is a cross-sectional view of the cylindrical inner mold 11 and the cylindrical outer mold 12 for explaining the filter manufacturing method, FIG. 5A is a plan view of the filter unit 21 constituted by the plastic filter 1, and FIG. It is a side view.
[0039]
A plastic filter 1 shown in FIG. 1 is formed of a porous body obtained by sintering a powdered thermoplastic material, and is configured as a hollow cylindrical body. The folds formed by alternately providing the outer bent portion 2a located at the outer peripheral end of the cylindrical body and the inner bent portion 2b positioned at the inner peripheral side of the cylindrical body are formed over the entire circumference of the cylindrical body. Yes. The

bent portions

2a and 2b are equally spaced at the same number of 8 locations, and their cross-sectional shapes (planar shapes) are star-shaped. In the plastic filter 1 shown in FIG. 2, the outer bent portions 2a and the inner bent portions 2b are equally spaced at the same number of 12 locations, and the cross-sectional shape thereof is also a star shape.
[0040]
The plastic filter 1 in FIG. 3 has a pleated portion formed by alternately providing an outer bent portion 2a located at the outer peripheral end of the cylindrical body and an inner bent portion 2b positioned at the inner peripheral side of the cylindrical body. The example formed over the half circumference of the body is shown. No pleats are formed in almost half the circumference of the cylindrical wall 3 (left half in the figure), and it has a substantially cylindrical shape, and the remaining half circumference (right half in the figure) of the cylindrical wall 3 has a star shape. There are seven outer bent portions 2a, while there are six inner bent portions 2b, which is one smaller than the number of outer bent portions 2a. In addition to the curved surface having a cylindrical shape, the cylindrical wall 3 may have a polygonal cylindrical shape in which a plurality of flat surfaces are connected, but a bent portion that is recessed toward the inner peripheral side is not provided. .
[0041]
In the illustrated plastic filter 1, examples of these preferable ranges for the thickness (t), the outer diameter (R1), the inner diameter (R2), and the number of pleats (n) of the cylindrical wall 3 are as follows. ) Is 20 to 150 mm, the inner diameter (R2) is {(2t + 1) n} × 1 / 2π to R1 × 0.8, the thickness (t) is 1 to 5 mm, and the number of pleats (n) is 6 or more. Is preferred.
[0042]
Here, the outer diameter (R1) is less than 20 mm, in other words, the inner cross-sectional area is 5 cm. ² If it is less than this, the [surface area of the filter / the volume of the dust collector] can be increased, which is preferable, but the practicality, particularly the filtration area or the area to be removed as the filter becomes too small, which is not preferable.
[0043]
In the production of the plastic filter of the present invention, a known production method can be applied when the plastic filter is formed into a porous body having a single layer structure, and the porous plastic substrate is a thermoplastic material having a predetermined particle size. A static molding method, a ram extrusion molding method, an injection molding method, a screw extrusion method using a molding die composed of an outer mold having a shape matched to the cross-sectional shape of the porous plastic filter and an inner mold inserted therein. It is obtained by sintering molding by a dynamic molding method such as a molding method. For example, the gap 13 formed by the cylindrical inner mold 11 and the cylindrical outer mold 12 having a cross-sectional shape as shown in FIG. 4 is filled with a powdered plastic material, which is heated at an appropriate temperature and sintered. , Obtained by demolding.
[0044]
As a method for producing a porous plastic filter having a multi-layer structure, various methods are conceivable depending on the shape of the filter, etc., but the following two methods that can reliably adjust the production efficiency and the thickness of each layer are preferable.
[0045]
[First method]
Using an outer mold that can be exchanged with an inner mold, and using a mold that can form a gap that can be filled with particles of thermoplastic material,
(1) First, a primary gap portion is formed which can form a layer thickness corresponding to the particle size of the thermoplastic material particles to be filled by placing an exchangeable outer die outside the inner die. After filling the plastic material of small diameter particles or large diameter particles into, this is sintered and molded into a small particle porous layer, or a porous plastic substrate of a large particle porous layer,
[0046]
(2) Next, the outer mold used earlier is removed and replaced with another outer mold having an inner diameter larger than the removed outer mold, and the secondary gap is formed on the surface layer side of the primary porous plastic substrate. Form the
[0047]
(3) Further, after filling the secondary gap with the large particle thermoplastic material having a particle size larger than that of the small particle thermoplastic material or the small particle thermoplastic material, Is sintered to form a large particle porous layer on the inner surface layer side of the small particle porous layer or a small particle porous layer on the inner surface layer side of the large particle porous layer.
[0048]
(4) After these are cooled, the outer mold and the inner mold are removed. As a result, a multi-layer porous plastic filter is obtained in which a small particle porous layer having a contact angle with water of 60 degrees or more, preferably 90 degrees or more is combined and integrated with the large particle porous layer.
[0049]
In addition, it is more convenient for sintering each layer of the multilayer porous plastic filter to be formed by the same kind of thermoplastic material, and it is also preferable from the viewpoint of interlayer adhesion of each layer.
[0050]
[Second method]
(1) First, a thermoplastic material having a predetermined particle diameter is subjected to primary sintering molding by an appropriate means as described above to form a porous plastic substrate.
[0051]
(2) Next, conductivity is imparted to the surface of the porous portion of the porous plastic substrate by the conductive material. In addition, when imparting electrical conductivity, for example, a method of mixing a conductive material such as carbon black, carbon fiber, or metal powder into the substrate when molding the porous plastic substrate, This is performed by a method of applying a liquid such as a surfactant to the surface. Usually, a method of applying a surfactant or the like is taken, but it is not particularly limited as long as it can impart conductivity to at least the surface of the porous plastic substrate.
[0052]
(3) Subsequently, a plastic having a particle size smaller than that of the particles constituting the porous plastic substrate and having compatibility with the surface of the porous plastic substrate on the surface of the porous plastic substrate. A small particle plastic material is applied and laminated by an electrostatic coating method that ejects the material.
[0053]
(4) Further, the porous plastic substrate is secondarily sintered in a heating furnace set at a predetermined temperature. Thereby, it is possible to obtain a multilayer porous plastic filter in which a small particle porous layer having a contact angle with water of 60 degrees or more, preferably 90 degrees or more is combined and integrated with a large particle porous layer.
[0054]
The molding die used for these is a molding die composed of an outer mold and an inner mold in the static molding method described above in accordance with the cross-sectional shape of the porous plastic filter, an extrusion die and an injection molding in the dynamic molding method. For example, a mold.
[0055]
The porous plastic filter obtained as described above is usually combined with a plurality of filter units 21 as shown in FIG. 5, which are suspended vertically or horizontally in a container for a separator having a predetermined shape. It is attached by means and used as a separation device.
[0056]
A filter unit 21 shown in FIG. 5 is obtained by attaching the porous plastic filter 1 to a substantially plate-like support 22, and fitting one end of the plastic filter 1 to the support 22 having a hole or the like. The opening at the other end is closed with a lid 23.
[0057]
The support 22 and the lid 5 are made of metal, various synthetic resins such as hard polyolefin resin, thermoplastic resin such as polyvinyl chloride, reactive thermosetting resin, or the like. Resins are preferred from the viewpoint of moldability and dimensional stability.
[0058]
When it is necessary to impart conductivity to the filter unit, about 1 to 10% of carbon black is added to the ultrahigh molecular weight polyethylene when sintering the porous plastic filter, and the support and the lid Similarly, a conductive material added with carbon black is used for the body.
[0059]
When reactive liquid polyurethane resin is used, 3 to 10% by weight of carbon fiber having an average yarn length of 0.1 to 1.0 mm is added to the main component polyol and curing agent, resulting in small residual distortion and high dimensional accuracy. And antistatic performance are suitable.
[0060]
In addition, the filter unit composed of a filter in which the pleat portion is formed over almost a half circumference of the hollow cylindrical body is mainly provided in a separator container having a predetermined shape, the half circumference of which is cylindrical (the side where no fold portion is formed). ) With the top side (the side from which the particles to be removed fall) placed horizontally and attached to the separation device, the particles to be removed that have fallen do not accumulate in the pleats of the plastic filter. preferable. However, this filter unit may be suspended in the vertical direction and attached as a separation device in the same manner as the hollow cylinder with star pleats.
[0061]
【Example】
Examples of the present invention will be described below, but the scope of the present invention is not limited by the following examples. A porous plastic filter was produced with the contents described below, and performance evaluation as a filter was evaluated by the following method. The results are shown in each table.
[0062]
“Presence / absence of particle dropout” …… When filter particles are removed by backwashing, the filter particles are not dropped (○), and when filter particles are removed by backwashing, some filter particles are removed ( (Triangle | delta)) In the case of wiping off by backwashing, the thing which has fallen out of filter particle | grains was set as (x). Here, the filter particles refer to particles having non-adhesive properties provided on the filter surface or plastics constituting the filter.
[0063]
"Powder wiping off": Fine particles adhered to the filter surface by backwashing (◎), fine particles adhering to the filter surface by backwashing (○), The case where the fine particles adhering to the filter surface by backwashing were partly bad (Δ) and the case where the fine particles adhering to the filter surface by backwashing were bad were marked (x).
[0064]
“Particulate collection performance” …… No contamination of the fine particles that have fallen off into the fluid outflow side (○), or some admission of fine particles into the fluid outflow side (△) In addition, it was assumed that the fine particles that had been wiped out were mixed into the fluid outflow side (×).
[0065]
“Water contact angle / degree”: a numerical value measured by a goniometer-type contact angle measuring instrument (G-1 type manufactured by Elma).
[0066]
“Pressure loss / mmAq” is a value when air containing no fine particles is sucked at 1 m / min.
[0067]
[Example 1]
The final porous plastic made of ultra-high molecular weight polyethylene having an average particle size of 30 μm and a melt flow rate of 0.01 or less and having a molecular weight of 2 million, which is formed from a cylindrical inner mold and a cylindrical outer mold shown in FIG. Fill the gap with the width necessary to obtain a filter thickness of 3 mm, and heat it for 30 to 90 minutes at a temperature of 160 to 220 ° C. Got.
[0068]
[Comparative Example 1]
Necessary to obtain a final porous plastic filter thickness of 3 mm formed from a cylindrical inner mold and a cylindrical outer mold using an ultra high molecular weight polyethylene having an average particle size of 30 μm and a melt flow rate of 0.01 or less and a molecular weight of 2 million. This was filled in a gap having a wide width and heated at a temperature of 160 to 220 ° C. for 30 to 90 minutes to obtain a porous plastic filter having a cylindrical cross section with a thickness of 3 mm (the outer diameter is the same as in Example 1). The same).
[0069]
[Table 1]

[0070]
As shown in Table 1, in each example, the dropout of particles, the mixing of fine particles on the fluid outflow side, and the powder removal performance are satisfactory, but the star shape of Example 1 is satisfactory. This filter has a lower pressure loss than a circular filter and increases the filtration area per unit volume, so it is easy to select the filtration capacity, equipment capacity, installation area, etc. The top is also excellent.
[0071]
[Example 2]
The final porosity formed from an ultra-high molecular weight polyethylene having an average particle diameter of 30 μm and a molecular weight of 2 million having a melt flow rate of 0.01 or less, from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1. Fill the gap with a width necessary to obtain a 2 mm thick plastic filter and heat it for 30 to 90 minutes at a temperature of 160 to 220 ° C. to obtain a porous plastic filter with a star shape of 2 mm thick cross section It was.
[0072]
Example 3
Ultra high molecular weight polyethylene having an average particle diameter of 110 μm and a melt flow rate of 0.01 or less and a molecular weight of 4 million is formed from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1. Fill the gap with the width necessary to obtain the final porous plastic filter thickness of 3 mm, and heat it at a temperature of 160 to 220 ° C. for 30 to 90 minutes. The cross-sectional shape of the wall thickness of 3 mm is a star-shaped porous plastic. A filter was obtained.
[0073]
Example 4
An ultra high molecular weight polyethylene having an average particle size of 30 μm and a melt flow rate of 0.01 or less and a molecular weight of 2 million is formed from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1. A gap having a width necessary for obtaining a final porous plastic filter thickness of 2 mm is filled, and this is heated at a temperature of 160 to 220 ° C. for 30 to 90 minutes. A 2 mm thick porous plastic filter having a star-shaped cross section was obtained.
[0074]
[Table 2]

[0075]
As shown in Table 2, in Example 2, there was no dropout of particles or mixing of fine particles on the fluid outflow side, and there was no problem with the powder removal performance. As a result, a small amount of fine particles were found on the fluid outflow side. In Example 4, there was a problem with the powder wiping property. In addition, the pressure loss is not a problem in practical use, but Example 3 is particularly good.
[0076]
[Examples 5 to 9]
Ultra high molecular weight polyethylene having an average particle size of 40 μm and a melt flow rate of 0.01 or less and a molecular weight of 2 million, and a massive ultra high molecular weight polyethylene having an average particle size of 150 μm and a melt flow rate of 0.01 or less and a molecular weight of 4 million The final porous plastic filter thickness formed from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1 were mixed with each other at a ratio (% by weight) described in Table 3. A gap having a width necessary for obtaining 2 mm was filled, and this was heated at a temperature of 160 to 220 ° C. for 30 to 90 minutes to obtain a porous plastic filter having a star shape of a cross section having a thickness of 2 mm.
[0077]
[Table 3]

[0078]
As shown in Table 3, all of Examples 5 to 9 have no problem in terms of particle dropping and powder removal performance, and the pressure loss is slightly higher in Example 5 but there is no practical problem. In Example 9 in which the ratio of the small particle size material was low, some of the fine particles were mixed on the fluid outflow side.
[0079]
Example 10
An ultra high molecular weight polyethylene having an average particle size of 30 μm and a melt flow rate of 0.01 or less and a molecular weight of 2 million and a PTFE powder having an average particle size of 0.2 μm are mixed with 95% ultra high molecular weight polyethylene. The material for sintering was mechanically mixed with a blender so that the weight percent and the TFE powder were 5 weight percent. This material is filled into a gap having a width necessary to obtain a final porous plastic filter thickness of 2 mm formed from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1, and 160 to 220 Heating was performed at a temperature of 30 ° C. for 30 to 90 minutes to obtain a porous plastic filter having a star-shaped cross section having a thickness of 2 mm.
[0080]
Example 11
An ultra high molecular weight polyethylene having an average particle size of 30 μm and a melt flow rate of 0.01 or less and a molecular weight of 200,000 and a polyfluoroalkyl acrylate dissolved in a solvent, the mixing ratio of the ultra high molecular weight polyethylene is 99% by weight, And it mixed mechanically with the blender so that a polyfluoroalkyl acrylate component might be 1 weight%, and it was set as the material for sintering. This material is filled into a gap having a width necessary to obtain a final porous plastic filter thickness of 2 mm formed from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1, and 160 to 220 Heating was performed at a temperature of 30 ° C. for 30 to 90 minutes to obtain a porous plastic filter having a star-shaped cross section having a thickness of 2 mm.
[0081]
[Table 4]

[0082]
As shown in Table 4, in Examples 10 and 11, there is no problem in the particle drop-off and the powder drop-off performance, and the water contact angle which is one standard in evaluating the drop-off performance. Was also a big value. In Example 10, the reason why the PTFE particles do not fall off is not clear at present, but when the ultrahigh molecular weight polyethylene melts and expands in the mold, the PTFE particles are embedded within the ultra high molecular weight polyethylene particles to some extent. It is thought to be for this purpose. On the other hand, in Example 11, the reason why the polyfluoroalkyl acrylate does not fall off is considered to be that the lipophilic groups are aligned on the particle side of the ultrahigh molecular weight polyethylene and the perfluoroalkyl groups are densely aligned on the surface side due to overheating. It is done. Further, any pressure loss is not a problem in practical use.
[0083]
Example 12
Prepare a total of three cylindrical inner molds having a cross-sectional shape similar to that of Example 1 and two cylindrical outer molds having a diameter larger than that of the cylindrical inner mold and exchangeable. , The primary width necessary for obtaining an ultra high molecular weight polyethylene having an average particle size of 160 μm and a molecular weight of 4 million having a melt flow rate of 0.01 or less and having a layer thickness ratio of 70% of the final porous plastic filter thickness of 3 mm. Filled in the primary gap of a molding die composed of a cylindrical inner mold having a gap and a cylindrical outer mold, and this is heated at a temperature of 160 to 220 ° C. for 30 to 90 minutes, and a large particle size porous material having a large pore size After obtaining the layer, this cylindrical outer mold was subsequently replaced with a cylindrical outer mold having an inner diameter larger than that of the cylindrical outer mold, and the average particle diameter was 30 μm outside the large-diameter porous layer. The layer thickness of the ultra-high molecular weight polyethylene having a molecular weight of 2 million and a melt flow rate of 0.01 or less A large cylindrical outer mold is arranged by forming a secondary gap portion having a width necessary for the ratio to be 30% of the final porous plastic filter thickness of 3 mm, and the average grain is placed in the secondary gap portion. Filled with ultra high molecular weight polyethylene having a diameter of 30 μm and heated again at a temperature of 160 to 220 ° C. for 30 minutes, a small particle size porous layer having a small pore diameter is formed on the outer layer side of the cylinder, that is, the fluid inflow side. A two-layer porous plastic filter having a total wall thickness of 3 mm and having a large-diameter porous layer formed on the inner layer side, i.e., the fluid outflow side, was obtained.
[0084]
Example 13
Using the same cylindrical inner mold and cylindrical outer mold as in Example 12, first, an ultra high molecular weight polyethylene having an average particle size of 30 μm and a melt flow rate of 0.01 or less and having a molecular weight of 2 million is used. Filled into the primary gap of a molding die composed of a cylindrical inner mold and a cylindrical outer mold having a primary gap of a width necessary to obtain 30% of the final porous plastic filter thickness of 3 mm, and this is filled with 160 to 220 After heating at a temperature of 30 ° C. for 30 minutes to obtain a small particle size porous layer having a small pore size, the cylindrical outer mold was replaced in the same manner as in Example 13, the average particle size was 160 μm, and the melt flow rate was 0.01 The following ultra-high molecular weight polyethylene having a molecular weight of 4 million was provided with a cylindrical outer mold replaced with the outside of the small particle size porous layer so that the layer thickness ratio would be 70% of the total thickness of the filter. The secondary gap is filled and this is again 160 Heated at a temperature of 220 ° C. for 30 minutes, a large particle size porous layer having a large pore size is formed on the outer layer side of the cylinder, that is, the fluid inflow side, and a small particle size porous material having a small hole diameter is formed on the inner layer side of the cylinder, that is, the fluid outflow side. A two-layer porous plastic filter having a star-shaped cross section with a total thickness of 3 mm was obtained.
[0085]
Example 14
The final porosity formed from an ultra-high molecular weight polyethylene having an average particle size of 160 μm and a molecular weight of 4 million having a melt flow rate of 0.01 or less from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1. A porous plastic filter having a star-shaped cross section of ultrahigh molecular weight polyethylene is filled in a gap having a width necessary to obtain a 3 mm thick plastic filter and heated at a temperature of 160 to 220 ° C. for 30 to 90 minutes. Got.
[0086]
[Table 5]

[0087]
As shown in Table 5, in Examples 12 and 13, there is no problem of particle dropout or mixing of fine particles on the fluid outflow side, and the pressure loss is small and no problem, but in Example 14, the pore diameter is too large. Therefore, mixing of fine particles on the fluid outflow side was observed. The pressure loss is not a problem in practical use, but Example 14 is particularly good.
[0088]
Example 15
The final porosity formed from an ultra-high molecular weight polyethylene having an average particle diameter of 170 μm and a melt flow rate of 0.01 or less having a molecular weight of 4 million from a cylindrical inner mold and a cylindrical outer mold having the same cross-sectional shape as in Example 1. A gap having a width necessary for obtaining a 3 mm thick plastic filter was filled, and this was heated at a temperature of 150 to 200 ° C. for 60 minutes to obtain a porous plastic filter having a star shape of 3 mm thick cross section. After applying a surfactant to the surface of the porous plastic substrate to impart conductivity to the surface of the substrate, an ultra high molecular weight molecular weight of 2 million with an average particle size of 30 μm and a melt flow rate of 0.01 or less. Using an automatic electrostatic coating machine, polyethylene is used with a working voltage of 60 V and an atomizing air pressure of 1.5 kg / cm. ² The substrate was electrostatically coated, and a 200 μm thick porous layer was deposited and laminated on the surface of the substrate with an ultra high molecular weight polyethylene having an average particle size of 30 μm and a molecular weight of 2 million. This is further heated in a heating furnace at a temperature of 150 to 200 ° C. for 30 minutes, sintered and molded, and a two-layered meat in which a porous layer having a diameter smaller than the pore diameter of the substrate is deposited on the surface of the substrate. A porous plastic filter having a star shape with a cross section of about 3 mm in thickness was obtained.
[0089]
Example 16
An ultra high molecular weight polyethylene having an average particle size of 340 μm and a melt flow rate of 0.01 or less and a molecular weight of 3.3 million is formed, and a die having a cylindrical opening having a width necessary for obtaining a final porous plastic filter thickness of 3 mm at the tip. Sintering was performed with the provided ram type extruder to obtain a cylindrical porous plastic substrate having a thickness of 3 mm. This porous plastic substrate was electrostatically coated under the same electrostatic coating conditions as in Example 15, and the surface of the substrate was made of ultrahigh molecular weight polyethylene having an average particle size of 30 μm and a molecular weight of 2 million and having a thickness of 200 μm. The layers were deposited and laminated, and this was further sintered and molded under the same heating conditions as in Example 15, and a porous layer having a diameter smaller than the pore diameter of the substrate was deposited and laminated on the surface of the substrate. A porous plastic filter having a star shape with a cross section of about 3 mm in thickness was obtained.
[0090]
[Table 6]

[0091]
As shown in Table 6, in Examples 15 and 16 in which a plastic material having a small particle diameter is electrostatically coated, there is no dropout of particles or mixing of fine particles on the fluid outflow side, and the performance as a filter is excellent. ing. Also, the pressure loss is good.
[0092]
Example 17
Using the same cylindrical inner mold and cylindrical outer mold as in Example 12, first, an ultra high molecular weight polyethylene having an average particle size of 160 μm and a melt flow rate of 0.01 or less and having a molecular weight of 4 million was used. Is filled in the primary gap of a molding die composed of a cylindrical inner mold having a primary gap having a width necessary to obtain 70% of the final porous plastic filter thickness of 3 mm, and the molding mold 160 to 160. After heating at a temperature of 220 ° C. for 30 minutes to obtain a large pore size porous layer having a large pore size, the cylindrical outer mold was replaced in the same manner as in Example 12, and 200 KGy of low density polyethylene having an average particle size of 26 μm was replaced with 200 KGy. A plastic material having a small particle diameter of 77% (melt flow rate of 0.01 or less) obtained by irradiating γ-rays is formed so that the layer thickness ratio is 30% of the total thickness of the filter. Cylindrical outside replaced with outside of the porous layer Is filled in the secondary gap provided, and heated again at a temperature of 160 to 220 ° C. for 30 minutes, and a small-sized porous material having a small pore diameter on the outer layer side of the cylinder, that is, the fluid inflow side. A porous plastic filter having a star-shaped cross section with a total wall thickness of 3 mm was obtained, with two layers having a large particle size porous layer with a large pore diameter formed on the inner layer side of the cylinder, that is, on the fluid outflow side. .
[0093]
Example 18
A porous plastic filter having an average particle diameter of 170 μm and an ultrahigh molecular weight polyethylene having a molecular weight of 4 million and a star shape of a cross section having a thickness of 3 mm was obtained in the same manner as in Example 15. After applying a surfactant to the surface of the porous plastic substrate to impart conductivity to the surface of the substrate, a plastic material having a small particle size of 77% similar to that used in Example 17 was used. Then, electrostatic coating was performed by the same electrostatic coating method as in Example 15, and a porous layer having a thickness of 170 μm was deposited and laminated on the surface of the base material with an ultra high molecular weight polyethylene having an average particle size of 26 μm. Sinter-molded under the same heating conditions as in Example 15, and a two-layered cross-sectional shape with a thickness of about 3 mm was formed into a star shape by laminating a porous layer having a diameter smaller than the pore diameter of the substrate on the surface of the substrate. A porous plastic filter was obtained.
[0094]
[Table 7]

[0095]
As shown in Table 7, a plastic material with a small particle size of 77% obtained by irradiating low density polyethylene with 200 KGy γ rays is inserted into an outer mold having a cylindrical shape and the like. In Examples 17 and 18 of the static molding method using an inner mold and the electrostatic coating method, there is no dropout of particles or mixing of fine particles on the fluid outflow side, and the performance as a filter is sufficient. In preparation. Also, the pressure loss is good.
[0096]
Example 19
Using the same cylindrical inner mold and cylindrical outer mold as in Example 12, first, the average particle size is 150 μm and the bulk density is 0.42 g / cm. ^Three A cylindrical inner mold having a primary gap portion having a width necessary for obtaining 70% of the final porous plastic filter thickness of the ultra-high molecular weight polyethylene having a molecular weight of 4,000,000, which is a vine-like molecular weight, and a final porous plastic filter thickness of 3 mm After filling the inside of the primary gap portion of the molding die comprising a cylindrical outer mold and heating it at a temperature of 160 to 220 ° C. for 30 to 90 minutes to obtain a large particle size porous layer having a large pore size, Example In the same manner as in No. 12, the outer cylindrical mold was replaced, and an ultra high molecular weight polyethylene having an average particle diameter of 40 μm and a melt flow rate of 0.01 or less and a molecular weight of 2 million was used, and the layer thickness ratio was 30% of the total thickness of the filter As shown in the figure, the outer space of the large-diameter porous layer is filled with a gap formed by replacing the tubular outer mold, and this is again filled at a temperature of 160-220 ° C. for 20-30. Heat up the part, and make holes on the outer layer side of the cylinder, that is, on the fluid inflow side. Two layers having a small-diameter porous layer with a small diameter and a large-diameter porous layer with a large pore size on the inner layer side of the cylinder, that is, the outflow side of the fluid. A quality plastic filter was obtained.
[0097]
Example 20
Using the same cylindrical inner mold and cylindrical outer mold as in Example 12, first, the average particle size is 120 μm and the bulk density is 0.46 g / cm. ^Three A cylindrical inner mold and a cylinder having a primary gap portion having a width necessary for obtaining a mass ratio of 70% of the final porous plastic filter thickness of the ultra-high molecular weight polyethylene having a molecular weight of 4 million in which the resin particles are massive and having a layer thickness ratio of 3 mm After filling in the primary gap part of the molding die composed of the outer mold and heating it at a temperature of 160 to 220 ° C. for 30 to 90 minutes to obtain a large particle size porous layer having a large pore size, Example 12 and In the same way, the cylindrical outer mold is replaced, and an ultra-high molecular weight polyethylene having an average particle size of 40 μm and a melt flow rate of 0.01 or less and having a molecular weight of 2 million is set so that the layer thickness ratio is 30% of the total thickness of the filter. In the secondary gap portion provided by arranging the cylindrical outer mold replaced with the cylindrical outer mold outside the large-diameter porous layer, and this is again filled at 20 to 30 at a temperature of 160 to 220 ° C. And heat up the hole on the outer layer side of the cylinder, that is, on the fluid inflow side. The small, small-diameter porous layer is composed of two layers with a large-diameter porous layer with a large pore diameter on the inner layer side of the cylinder, that is, the fluid outflow side. A shaped porous plastic filter was obtained.
[0098]
[Table 8]

[0099]
As shown in Table 8, in Example 19 in which the resin particles used were ultra high molecular weight polyethylene in the shape of grape bunches, high tensile strength and elongation were exhibited without causing a decrease in pressure loss. In Example 20, the pressure loss is not reduced, but the tensile strength and elongation are reduced.
[0100]
【The invention's effect】
The porous plastic filter for separating fine particles composed of a hollow cylindrical body having pleats formed on the entire circumference or almost half the circumference according to the present invention is, of course, assembled when used as a single filter element. When used as a filter unit, it is possible to have a filtration area that is 1.5 to several times as large as that of a simple cylindrical unit, and when this is incorporated into a dust collector, The size can be reduced to 1/2 to 1/3 or less, and a great industrial effect is achieved.
[0101]
Moreover, since the porous plastic filter of the present invention is formed by sintering a powdered thermoplastic material, it is a porous body having various excellent properties as a filter, and has rigidity. It is a self-upright or form-retaining filter that does not require a supporting device (retainer) for maintaining the shape of the filter element or filter unit.
[0102]
In addition, the porous plastic filter of the present invention has a good wipe-off performance because the contact angle with water on the surface of at least one side of the hollow cylindrical body is 60 degrees or more, preferably 90 degrees or more.
[0103]
Further, as a powdered thermoplastic material, a configuration using a thermoplastic material A having an average particle size of 5 to 90 μm, a plastic material A having an average particle size of 5 to 90 μm, and an average particle size exceeding 90 μm , And a small particle porous layer formed by sintering a plastic material A having a small average particle diameter, and an average particle diameter larger than that of the plastic material A The structure comprising a composite integral layer with a large particle porous layer formed by sintering plastic material B has both good removal performance and surface collection performance, but also has PTFE particles as in the past. The porous plastic filter for separating fine particles can be provided which has no problem of falling off and mixed into the collected fine particles.
[Brief description of the drawings]
FIG. 1A is a plan view and FIG. 1B is a perspective view of a plastic filter 1 as an example of an embodiment of the present invention.
FIG. 2 is a plan view of a plastic filter 1 of another example.
FIG. 3 is a plan view of another example of a plastic filter 1;
FIG. 4 is a cross-sectional view of a cylindrical inner mold 11 and a cylindrical outer mold 12 for explaining a method for producing a plastic filter.
5A is a plan view and FIG. 5B is a side view of a filter unit 21 constituted by the plastic filter 1. FIG.
[Explanation of symbols]
1 Plastic filter
2a Outer bend
2b Inner bend
3 cylinder wall
11 cylindrical inner mold
12 cylindrical outer mold
21 Filter unit
22 Support
23 Lid

Claims

A porous material for separating fine particles, comprising a porous body obtained by sintering a powdered thermoplastic material and having a pleated portion formed on at least a part of a cylindrical wall. Plastic filter.

2. The porous plastic filter for separating fine particles according to claim 1, wherein a contact angle of at least one surface of the hollow cylindrical body with respect to water is 60 degrees or more.

3. The porous plastic filter for separating fine particles according to claim 1, wherein a plastic material A having an average particle size of 5 to 90 [mu] m is used as the powdered thermoplastic material.

As the powdered thermoplastic material, at least a plastic material A having an average particle diameter of 5 to 90 μm and a plastic material B having an average particle diameter of more than 90 μm and 1,000 μm or less are used. The porous plastic filter for fine particle separation according to claim 1 or 2.

The hollow cylindrical body is formed by sintering at least a small particle porous layer formed by sintering a plastic material A having a small average particle diameter and a plastic material B having an average particle diameter larger than that of the plastic material A. 5. The porous plastic filter for separating fine particles according to claim 1, 2 or 4, further comprising a composite monolithic layer with a large porous layer formed into a shape.

The porous plastic filter for separating fine particles according to claim 3, 4 or 5, wherein the plastic material A is ultra high molecular weight polyethylene having an average particle diameter of 10 to 60 µm.